Continuous positive airway pressure (CPAP) or alternatively, Bilevel Positive Airway Pressure (BiPAP) have become conventional forms of non-invasive ventilation treatment for adult patients suffering from obstructive sleep apnea and other nocturnal breathing disorders. Furthermore, not only has it been shown to be an effective therapy, but there is also evidence that it contributes to less time in hospital, fewer medical complications and decreased mortality compared to immediate intubation and ventilation.
Continuous positive airway pressure (CPAP) is delivered by a positive airway pressure generator into a mask worn by the patient while sleeping. This effectively dilates the upper airway, preventing its collapse, thus enabling the patient to assume a normal breathing pattern which results in an uninterrupted sleep. For many patients this therapy dramatically improves their daytime functioning and behaviour as well as their general health.
BiPAP delivers CPAP but also has the capability to sense when an inspiratory effort is being made by the patient and, in turn, delivers a higher pressure during inspiration. When flow stops, the pressure returns to the CPAP level. This positive pressure wave during inspirations unloads the diaphragm, decreasing the work of breathing and has been found particularly useful in patients with chronic respiratory failure due to neuromuscular weakness or dysfunction or chest wall abnormalities.
One study showed that the use of CPAP has resulted in a reduction of intubation from 74% to 16%, major complications were decreased from 48% to 16% and length of stay in hospital was reduced from 35 days to 23 days. Mortality was decreased from 29% to 9%. There is also evidence from randomized, controlled trials to show that CPAP improves oxygenation, hypercapnia and reduces the rate of endotracheal intubation in pulmonary edema.
More recently, CPAP has become a therapy of choice for pediatric patents suffering from abnormal breathing during sleep resulting from among others, small upper airways, upper airway resistance syndrome, persistent obstruction following surgery for adenotonsillar hypertrophy, craniofacial anomalies, neuromuscular weakness, obesity, spina bifida and Down's Syndrome. In many cases, standard invasive respiratory intervention such as tracheostomies and intubation can be avoided. Sleep apnea has also been reported in infants considered to be at risk of death from sudden infant death syndrome (SIDS) and has been seen in infants who have subsequently died of SIDS.
Much of the information relating to compliance problems associated with CPAP are reported from adult studies. Clearly, adults are better able to provide feedback to health care providers, regarding those issues which prevent or limit their ability or desire to utilize the therapy. It can be extrapolated however, that these issues are also present for the pediatric patient and, in many cases, are made worse due to the patient's lack of understanding of the therapy and fear of intervention, as well as the commercial unavailability of a wide variety of sizes or well fitting masks and headgear.
The major reported obstacle for most adult patients to overcome is becoming accustomed to the ventilation system. Approximately 20% of patients, for a variety of reasons, never learn to tolerate it and a substantial proportion of the others have a hard time using it regularly. The statistics for use in pediatric patients can be much worse. Kribbs et al. reported in the American Journal of Respiratory Diseases in 1993 that only 6% of the 35 CPAP patients studied used CPAP 70% of the time for 7 hours or greater, suggesting that frequent, long duration usage of nasal CPAP is a rare occurrence in obstructive sleep apnea (OSA). Efforts to enhance CPAP and BiPAP use are needed especially early in treatment to reduce the significant nature of the disorder and death associated with OSA and nocturnal hypoventilation. Problems such as mask fit, pressure sores or redness around the nose and nasal dryness or stuffiness are common reasons that patients fail to comply. Most of these problems are solvable by finding a mask that fits properly.
Air leaking from around a poorly fitting nasal mask can be quite uncomfortable and possibly result in suboptimal treatment. Air leaking causes the generator to blow more air to achieve the prescribed pressure, thus making it more uncomfortable for the patient and possibly causing more arousals during sleep. In many cases, the air is directed from the poorly fitting mask directly into the patient's eyes. For this reason, it is essential that the mask fit properly, which is particularly challenging in the case of children. Further, as the patient drifts off to sleep, the jaw tends to relax and the mouth may open. When this happens, air from the generator may escape through the mouth. A properly fitting chin strap can assist in keeping the mouth closed during sleep.
Headgear is used to hold the mask in place over the nose, or over the nose and mouth, in the case of a full-face mask. Typically, headgear comprises a plurality of straps connected to the mask, which extend about the head or to a cap fitted on the head, to stabilize the mask.
Pediatric patients may be introduced to CPAP from the time of birth and may continue to require treatment throughout their entire lives. Clearly nasal and full-face masks designed to fit the adult face are unsuitable for these patients, especially in their early years. Craniofacial abnormalities may add to the difficulty in finding a mask that fits well. Further, it has been reported that children wearing an improperly fitting mask during bone development can develop facial abnormalities as a result of the poorly fitting mask.
Nasal prongs or nasopharyngeal tubes, that may be used in a hospital setting to deliver CPAP, are not available for equipment designed for the home environment. As well, most manufacturers provide only one size of mask for pediatric patients, if they provide a pediatric mask at all. Currently, to Applicant's knowledge there are no masks marketed as “pediatric masks” that are small enough to fit premature neonatal patients satisfactorily. It appears that there is little recognition that a unique range of sizes is required for the pediatric population, which extends, in age, from neonate to pre-teen. Patients who have syndromes that result in stunted growth may require pediatric sized masks throughout their lives.
Currently, masks and headgear may be sold as a pre-packaged system, however, a mask from one system may be better suited with the headgear from another, for a particular patient. Costs escalate if pre-packaged systems are purchased, but only one of the components is usually used, due to fit or comfort considerations, in combination with a component from another system. Often, a suitable component is not available at all and the therapist and patient must “make do” with the closest alternative, which is often uncomfortable and heavy and as a result little used.
One system intended specifically for pediatric use, known to Applicant, is the Resmed Infant Mask System having a nasal mask and a cap (RESCAP™). Resmed is an Australian Corporation. A single strap extends from a point at the front of the cap to a tab extending from the top of the mask, between the eyes, which acts as a forehead support and has a cushion designed to rest against the forehead to reduce pressure sore formation. A second strap extends through the forehead support and around the patient's head to the sides of the cap. Third and fourth straps extend from protruding tabs at the sides of the mask to join the cap adjacent it's bottom edge. The straps are attached to the mask and to the cap using Velcro™.
A single, flexible cuff is formed about the nasal mask to accommodate and seal about the nose. While the mask is small enough to fit some pediatric patients, the cuff must often be retrofit or cut to fit over individual patient's noses. Once the cuff has been cut to provide a better fit for slightly larger noses or abnormalities, the cut edges are likely to cause irritation at the points of contact or leaks where there is insufficient sealing. Further, the cushioned forehead support continues to cause pressure sores, especially in the smallest of the patients where the headgear may not fit adequately and the mask moves about. The mask shell is generally triangular in shape and has a flat surface into which a port is formed and tubing is attached. For many patients, the flat surface of the mask shell does not permit adequate space for the nose and as a result the nose rests against the surface often resulting in pressure sores.
Many of the pediatric patients are non-compliant and may fall asleep periodically throughout the day and night. The Velcro™ fasteners are difficult to adjust without arousing the child. More importantly, if the child has fallen asleep in an awkward position, it is difficult to ensure that the mask is positioned correctly and snuggly on the face, as the length of the straps are dependant on where the fasteners are fastened each and every time the mask is worn.
Typically, patients introduced to CPAP at the toddler stage of development, exhibit great resistance to use of the mask. At least in part this resistance develops because of comfort issues, including size which may obstruct their vision, pressure sores as a result of contact points on the forehead and cheeks, excessive weight or, in some cases, latex allergies and may further include psychological reasons. Many of these patients have spent considerable time in institutions, such as hospitals, and have been subjected to almost constant medical intervention of one type or another. Placing a mask on the face may elicit fear of the apparatus itself or what it is perceived to be associated with and particularly for those who have become tactile defiant, compliance becomes a struggle that many parents and therapists are unable to resolve.
Often psychologists are included as an integral part of the therapy team as they attempt to improve the pediatric patient's compliance with CPAP or BiPAP therapy. In some cases, all members of a family are encouraged to also wear a mask while preparing the patient and their siblings for bed so that the patient views it as a “normal” process in the bedtime ritual. The mask may be included among a child's toys so that they come to see it as something fun rather than a medical device. Games are created around the issue of wearing the mask. Often several months are spent in this process during which little or no therapy is actually occurring. For some patients, the loss of time may be critical to their overall health and may result in the need to proceed to more conventional invasive techniques such as tracheostomy, without giving the therapy a chance.
One product used to improve nebulizer compliance in asthmatic children is the “Bubbles The Fish” pediatric aerosol mask for use with a PARI nebulizer. The mask is transparent, but made to look like a fish face so that children find it fun to use, greatly improving compliance. The aerosol mask however, cannot be used to administer CPAP, as it is designed to be hand held over the nose and mouth for short-term use for inhalation only, rather than attached to headgear for continuous use. Size and configuration are less important for this type of therapy, typically requiring only a “one size fits all” mask.
The range of mask and headgear sizes required for the pediatric population may represent very small incremental and visually indistinct changes in dimensions. For this reason it is desirable to have a system for simple recognition of the different sizes available, especially when systems are further obscured when pre-packaged.
Clearly, there is a need for a ventilation mask and associated headgear that is available to fit pediatric patients ranging from the tiniest of neonates to those nearly able to wear small adult sized apparatus. Such a system would be comfortable, viewed as something desirable to wear by the patient and readily identifiable as to its size for ease of fitting.